MSCs Induce Brain Plasticity via tPA

描述(由申请人提供)：基于细胞的疗法在减少与中风相关的神经缺陷方面显示出巨大的前景。其中最有效的疗法之一是骨髓基质细胞(MSCs)，已被证明具有高度的神经修复作用。在这一应用中，我们将研究MSCs产生这种神经修复作用的机制。我们的初步数据有力地表明，MSC治疗中风促进了脑神经突起的重塑。我们认为，在卒中后给予MSCs，可激活实质细胞内的组织纤溶酶原激活物(TPA)，tPA介导轴突重塑，从而改善神经功能。因此，假设1：a)MSCs增加实质细胞中tPA活性；b)tPA活性增加增加轴突重塑；c)轴突重塑增加有助于改善卒中后的功能转归。假设2：a)MSCs通过Shh信号通路上调星形胶质细胞、神经元和内皮细胞的tPA活性；b)MSCs通过Shh信号通路下调TGF-β1/PAI-1，从而提高tPA活性。假说3：骨髓间充质干细胞通过纤溶酶依赖的蛋白水解酶裂解前神经营养因子促进轴突重塑：前神经生长因子(Pro-NGF)为NGF，前脑源性神经营养因子(PRO-BDNF)为BDNF。这些假说剖析了外源性MSCs和内源性实质细胞的相互作用及其对卒中后tPA活性、轴突重塑和神经功能的影响。我们的研究使用了转基因tPA-/-、PLG-/-小鼠以及我们实验室一系列新颖和成熟的实验技术。据我们所知，我们的工作是第一次将tPA活性作为一个关键的统一因素来研究，以放大中枢神经系统中外源细胞的有益活动。这个项目是一个连贯和高度相互交织的努力，旨在阐明分子和细胞途径，通过这些途径，受损的大脑可以通过基于细胞的治疗来重塑。我们的最终目标是描述中风恢复性治疗中基于细胞的治疗的机制基础。我们的研究对所有神经疾病和损伤的治疗意义是显而易见的。 公共卫生相关性：我们的研究将提供基本的洞察力，了解如何使用基于细胞的治疗来重塑受损的大脑和改善神经功能。使用外源性给药细胞的恢复性治疗不受治疗窗口狭窄的限制，可以适用于所有中风患者。我们的目标是确定这些被管理的细胞如何与内源性脑细胞相互作用，这可能会使基于细胞的恢复性治疗中风和神经损伤的治疗取得成果。

DESCRIPTION (provided by applicant): Cell-based therapies have shown enormous promise in reducing neurological deficits associated with stroke. One of the most effective of these therapies is bone marrow stromal cells (MSCs), that has been demonstrated to be highly neurorestorative. In this application, we will investigate the mechanisms by which MSCs produce this neurorestorative effect. Our preliminary data strongly indicate that MSC treatment of stroke promotes neurite remodeling of brain. We propose that when administered after stroke, MSCs activate tissue plasminogen activator (tPA) within parenchymal cells, and tPA mediates neurite remodeling leading to improvement in neurological function. Therefore, the following three hypotheses are tested: Hypothesis 1: a) MSCs increase tPA activity in parenchymal cells; b) Increased tPA activity increases neurite remodeling; c) Increased neurite remodeling contributes to improvement of functional outcome after stroke. Hypothesis 2: a) MSCs up-regulate tPA activity in astrocytes, neurons and endothelial cells via the Shh signaling pathway; b) MSCs down-regulate TGF-¿1/PAI-1 via the Shh signaling pathway and thereby increase tPA activity. Hypothesis 3: tPA activity increased by MSCs promotes neurite remodeling via plasmin-dependent proteolytic cleavage of pro-neurotrophins: pro-nerve growth factor (pro-NGF) to NGF, pro-brain derived neurotrophic factor (pro-BDNF) to BDNF These hypotheses dissect the interactions of exogenous MSCs and endogenous parenchymal cells and their affect on tPA activity, neurite remodeling and neurological function after stroke. Our studies employ genetically modified tPA-/-, Plg-/-mice as well as an array of novel and well-established experimental techniques in our laboratory. To our knowledge, our work is the first to investigate tPA activity as a key unifying factor to amplify beneficial actions of exogenous cells in the CNS. This project is a coherent and highly interwoven effort to elucidate the molecular and cellular pathways by which injured brain can be remodeled by cell-based therapies. Our ultimate goal is to delineate the mechanistic underpinnings of cell-based therapy in the restorative treatment of stroke. The therapeutic implications of our studies for all neurological disease and injury are evident. PUBLIC HEALTH RELEVANCE: Our study will provide essential insight into how the injured brain is remodeled and neurological function improved using a cell-based therapy. Restorative therapy using exogenously administered cells is not limited by a narrow therapeutic window and can be administered to all stroke patients. Our goal to identify how these administered cells interact with the endogenous brain cells will likely bring to fruition restorative cell-based therapy for the treatment of stroke and neural injury.